The footprint of coal

No agency of the United States government has published nationwide figures for the number of acres disturbed in the process of mining coal since the U.S. Geological Survey conducted a nationwide survey in the mid-1970s. Nevertheless, it is possible to build an estimate by adding the now-outdated USGS figures to more current data provided by individual states to the U.S. Office of Surface Mining Reclamation and Enforcement (OSM)as part of the annual reporting process required by the Surface Mining Control and Reclamation Act (SMCRA).

Notes on the estimates: The estimates on this page do not include the additional disturbance to land caused in the vicinity of coal mines by coal processing, transportation, sludge storage, or power plants. To fully estimate the land-use footprint of coal power, all these factors need to be taken into consideration.

Estimate: 27.3 billion tons
Background and calculations:

The following are estimates of the amount of coal produced by surface mining since 1914.


 * 1914 - 1948: 1,266.7 million tons
 * 1949 - 2009: 26,059.2 million tons
 * TOTAL for 1914 - 2009: 27,325.9 million tons

Estimate: 8.4 million acres
Background and calculations:

Pre-1977 data: In 1977, a representative of the U.S. Army Corps of Engineers testified at the House hearings on the Surface Mining Control and Reclamation Act that more than 4.4 million acres of land had been disturbed by surface mining in the United States, according to a National Strip Mine Study prepared by the Corps. The Army Corps representative also testified that the annual rate of land disturbance by surface miing was 153,000 acres in 1964 and 207,000 acres in 1974.

1977-2008 data: In the absence of specific data on acres mined, which are not comprehensively reported either by states or by OSM, the most comprehensive data available for estimating the amount of land disturbed by surface mining comes from the "new acres permitted" figures reported annually by the Office of Surface Mining Control and Reclamation (OSM). For the years 1996-2008, a total of 1,560,984 acres were permitted in the United States, including 1,496,695 acres outside Wyoming and 64,289 acres in Wyoming. During that period, 9.585 billion tons of coal were produced by surface mining in the United States as a whole, including 4.820 billion tons in Wyoming and 4.765 billion tons outside Wyoming. Based on these acreage and tonnage figures, the land intensity of surface mining is 314.1 acres per million ton outside Wyoming and 13.3 acres per million ton inside Wyoming. Extrapolating these land intensity rates to the period 1977-1995 (7.528 billion tons produced outside Wyoming, 2.727 billion tons produced in Wyoming) results in an estimate of 2,365,000 acres mined outside Wyoming and 36,000 acres mined in Wyoming, or a total of 3,961,984 acres disturbed nationwide by surface mining for the period 1977-2008.

Total estimate: Adding the U.S. Army Corps of Engineers pre-1977 estimate (4.4 million acres) to the 1977-2008 estimate based on OSM figures (4.0 million acres) results in an estimate of 8.4 million acres (13,125 square miles) disturbed through 2008 by surface mining in the United States.

Other estimates: According to the National Mining Association, the amount of land that has been mined to produce coal in the U.S. amounts to "approximately five million acres." However, the NMA does not publish the source of that figure or specify the time period. Since the NMA figure is only slightly higher than the 4.4 million-acre estimate of the U.S. Army Corps of Engineers in 1977, it appears to be a low estimate. A 1979 paper by Lowell Catlett of New Mexico State University and Michael Boehlje of Iowa State University estimated the amount of land disturbed by surface mining from 1870 to 1930 at 250,000 acres and for the period 1930 to 1971 at 3,357,000 acres of land, or 3.6 million acres for the period 1930-1971. This estimate is roughly compatible with the U.S. Army Corps of Engineers estimate, which is 800,000 acres larger but includes additional years of production after 1971.

Estimate: 1.2 million acres
Background and calculations:

Mountaintop removal mining is a particularly destructive form of surface mining used most intensively in Appalachia. In Central Appalachia (eastern Kentucky and Tennessee, southern West Virginia, western Virginia) the area disturbed by mountaintop removal has been directly measured by a survey published in 2009 by Appalachian Voices based on satellite and permit data. The survey reported that 1,160,000 acres in Central Appalachia had been disturbed by surface mining, including the following state-by-state totals: eastern Kentucky 574,000 acres, Tennessee 78,000 acres, Virginia 156,000 acres, southern West Virginia 352,000 acres. The data was based on 2006 imagery for Tennessee and Kentucky, 2007 imagery for West Virginia, and 2008 imagery for Virginia.

National estimate for U.S. (excluding Wyoming): 314.1 acres per million tons
Background and calculations for national estimate:


 * For the years 1996-2008, OSM's annual reports show that 1,560,984 acres were permitted for surface mining in the United States, including 64,289 acres in Wyoming and 1,496,695 acres in other states. Production by surface mining over the same 1996-2008 period was 9.585 billion tons nationwide, including 4.820 billion tons in Wyoming and 4.765 billion tons in other states. Based on these figures, the land intensity of surface mining during this period was 162.9 acres per million tons nationwide, or 314.1 acres per million tons outside Wyoming and 13.3 acres per million tons in Wyoming.

State-by-state estimates
As the table below shows, the number of acres that must be disturbed to produce a ton of coal varies widely from state to state. Among the states shown in the table, Wyoming's land intensity figure based on mining in 2009 is the lowest at 12.8 acres per million tons produced by surface mining, while Tennessee's is the highest at 622.2 acres per million tons. This is because Wyoming's coal seams are typically 80 or more feet thick, whereas coal in Tennessee surface mines derives from thinner seams that are typically accessed via highly disruptive mountaintop removal mining.

TABLE 1: Acres disturbed by coal mining (2009).

(To sort the table, click on a column header.)

Source: ''"NR" stands for "not reported." The "acres disturbed" figures in the table above are derived from individual state reports provided to the U.S. Office of Surface Mining Reclamation and Enforcement. The production figures are from the U.S. Energy Information Administration. Data for acres disturbed are for the 12 months ending on June 30, 2009, while the production figures are for the 2009 calendar year.''

TABLE 2: Acres disturbed by coal mining (based on average acres permitted 1996-2008).

(To sort the table, click on a column header.)

Notes: ''The "acres permitted" figures in the table above are the yearly average from 1996-2008 derived from the annual reports published by the U.S. Office of Surface Mining Reclamation and Enforcement. The production figures are yearly averages for 1996-2008 derived from the U.S. Energy Information Administration. ''

Estimate for 2009: 104,000 acres (162.5 square miles)
Background and calculations:

From 1996-2008, the average land-use intensity of surface mining in the United States was 13.3 acres per million tons of Wyoming coal and 314.1 acres per million tons of non-Wyoming coal. (See calculation above under "How much land is currently disturbed per million tons of surface-mined coal in the United States?") In 2009, U.S. production from surface mining was 427,635,000 tons from Wyoming and 313,469,000 tons from other states. Based on these figures, U.S. surface mining disturbed about 104,000 acres (162.5 square miles) in 2009.

Estimate for 2009: 13,235 acres
Background and calculations:

Longwall mining, a form of underground mining designed to completely remove underground coal seams, results in land subsidence over large areas. As documented by reports describing subsidence impacts in Pennsylvania and elsewhere, longwall mining produces serious impacts to buildings, surface water supplies, aquifers. In 2009, longwall mining accounted for 166.4 million tons of coal, or 50% of U.S. underground coal production. This included 101.2 million tons in Appalachia, 12.2 million tons in the Illinois basin, and 53.1 million tons in the West. According to the Energy Information Administration, longwall mine seam heights average 71 inches in Appalachia, 86 inches in the Illinois Basin, and 127 inches in the West. Assuming 1800 tons of recoverable coal per acre foot, the amount of surface area affected by longwall mining in 2009 was 13,235 acres.

TABLE 4: Longwall coal production, area disturbed, and land intensity by region (2009)

Sources: "Underground production by state and mining method, 2009," Energy Information Administration; "Longwall Mining," Table 4: Average Mining Height of Longwall Units, by State and Region, Energy Information Administration, DOE/EIA-TR-0588, March 1995. Note: Appalachia includes Alabama, Eastern Kentucky, Maryland, Ohio, Pennsylvania, Virginia, and West Virginia. Illinois Basin includes Illinois and Wesetrn Kentucky. West includes Colorado, New Mexico, Utah, and Wyoming.

Estimate: Solar thermal energy requires about 16.4% less land than coal, and wind power requires about 96.3% less land than coal, to produce a given amount of electricity over a 60-year period.
Background and calculations:

A common contention among writers on energy is that fossil fuels sources are more "concentrated" and therefore require less land than "diffuse" energy sources such as wind and solar. For example, Richard W. Fulmer writes:


 * The reason that solar power, wind power, and ethanol are so expensive is that they are derived from very diffuse energy sources. It takes a lot of energy collectors such as solar cells, wind turbines, or corn stalks covering many square miles of land to produce the same amount of power that traditional coal, natural gas, or nuclear plants can on just a few acres.

For both solar thermal power and wind power, the available data on current amounts of land used to produce electricity indicate that coal requires that more land be disturbed.


 * Solar thermal: In 2009, the United States produced 1,764,486 Gigawatt-hours (GWh) of electricity from coal (including both underground and surface production). Based on the estimate of 104,000 acres of land disturbed by coal surface mining (see above) and 13,235 acres disturbed by longwall mining subsidence (see above), or 117,235 acres total, U.S. electricity generation from coal produced 15.051 GWh per acre of land disturbed. The Blythe solar thermal plant proposed for California's Mohave Desert would produce 2100 GWh per year using 7,000 acres of land, or 126,000 GWh over a 60-year period. This suggests a land footprint for solar thermal energy of 18 GWh per acre of land disturbed.


 * Wind power: Assuming an average U.S. capacity factor of 25.7, a footprint (including service roads) of 0.5 acres per turbine , a 3-megawatt wind turbine produces 405.2 GWh over a 60-year period. This suggests a land footprint for wind power of 810.4 GWh per acre of land disturbed. This means that the land footprint for wind power is 96.3 percent smaller than the land footprint for coal power.

Note: These comparisons do not take into account land used or disturbed by coal plants, coal waste facilities, or transportation of coal. The land estimates for coal power, solar energy, and wind do not include land used to manufacture components such as generators, turbines, draglines, or mirrors. The estimates do not include transmission lines or water impacts.

How much surface-mined is reclaimed?
The most comprehensive data on release of mining bonds on surface mined land provided in the Office of Surface Mining and Reclamation's annual reports. Performance bonds are typically released in three phases as reclamation proceeds. Phase I bond release occurs upon the completion of backfilling and grading of mined areas to their “approximate original contour” and replacement of topsoil. Phase II bond release requires erosion prevention and reseeding of disturbed terrain. Phase III bond release is granted once revegetation standards have been met, pre-mining productivity has been reestablished, and pre-mining surface and groundwater quality and quantity (including groundwater recharge capacity) have been restored. Table 3 shows the annual acreage of new mining permits and the annual acreage of mined land released from Phase III.

TABLE 3: Amount of land newly permitted for surface mining and amount of land released from Phase III bond

Source: Office of Surface Mining Reclamation and Enforcement Annual Reports, 1999-2008

Surface mines
The following is a partial list of large U.S. surface mines. All of these mines are still in operation. Note that figures for mines and mine complexes may include areas that are planned for future mining.


 * North Antelope Rochelle Mine (Wyoming): This mine produces more coal than any other mine in the United States. Between opening in 1983 and 2010, it has produced 1.3 billion tons of coal, with 859 million tons of recoverable coal remaining. The Wyodak-Anderson coal seam ranges from 60 to 80 feet in thickness. The remaining coal covers 28,000 acres (32.6 acres per million tons). Applying the 32.6 acres per million tons figure to the previously mined coal, the mine has already disturbed 42,375 acres. Based on those figures, the ultimate size of the area disturbed will exceed 70,000 acres.


 *  Black Butte Mine (Wyoming): This mine occupies more than 70 square miles (44,800 acres). As of 2010, 11,484 acres had been mined, and none had been received a final (Phase III) bond release.


 * Jewett Mine (Texas): This 35,000-acre mine, with five active pits, is owned by Westmoreland Coal.


 * Rosebud Mine (Montana): This 25,000-acre mine, which provides coal to the Colstrip Steam Plant, is owned by Westmoreland Coal.


 * Jim Bridger Mine (Wyoming): Owned by Warren Buffett's MidAmerican Energy, this mine has 9,938 acres of disturbed land with 3,587 acres reclaimed. According to the Office of Surface Mining's 2010 report, "Low ratios of reclmation to disturbance indicate that reclmaation is not progressing at the same rate as mining, resulting in an increasing acreage of disturbed lands." As of, the mine has 2,019 acres of Phase I bond release and no Phase II or Phase III bond release.


 * Cordero Rojo Mine (Wyoming): Created in 1997 by merging the Cordero and Caballo Rojo mines, this mine controls 6,500 acres of federal land containing approximately 350 million tons of coal (18.6 acres per million tons).


 * Jacobs Ranch Mine (Wyoming): 15,625 acres


 * Falkirk Mine (North Dakota): Began production in 1978. Mines 300-400 acres per year (11,200 acres mined from 1978-2010, assuming 350 acres per year); 56,000 acres under lease.


 * Beulah Mine (North Dakota): This 9,000-acre mine complex, with three active pits producing 3.0 million tons of lignite per year, is owned by Westmoreland Coal.


 * Hobet 21 Surface Mine (West Virginia): The Hobet Mine complex has been estimated at 10,000 acres. Photos here show the mine overlaid on 38 U.S. cities.


 * Black Thunder Mine (Wyoming): 1.5 billion tons of proven and probable reserves as of December 31, 2009; mining complex is 33,800 acres.


 * Arch of Wyoming Mine (Wyoming): The Arch of Wyoming complex consists of one active surface mine and four inactive mines located on approximately 58,000 acres.


 * Coal-Mac Mine (West Virginia): This underground and surface mining complex occupies about 46,800 acres.


 * Colowyo Mine (Colorado): This surface mine produces 3.4 million tons per year. The mine site is 12,000 acres.


 * Trapper Mine (Colorado): This surface mine produces 2.3 million tons per year. The mine site is 10,000 acres.


 * Lee Ranch Mine (Colorado): This surface mine produces 5.5 million tons per year. The mine site is 16,000 acres.


 * Dry Fork Mine (Colorado): This surface mine produces 5.6 million tons per year. The mine site is 7,000 acres, and an additional 4,160 acres of federal and Wyoming coal is under lease.

Longwall mines

 * Twentymile Mine (Colorado): Operated by Peabody Energy, this longwall mine produced 7.8 million tons of coal in 2009. The mine is located on 200,000 acres in the Uinta Coal Basin.


 * Bailey Mine (Pennsylvania): This CONSOL Energy mine encompassed 31,491 acres as of October 2009, and an expansion encompassing 3,135 acres has been proposed.


 * Emerald Mine (Pennsylvania): As of August 2009, this mine encompassed 21,047 acres, with a 3,071 acre expansion under review.


 * Enlow Fork Mine (Pennsylvania): This CONSOL Energy mine encompassed 35,215 acres as of November 2009.

Historical data on surface-mined coal
Prior to World War I, data is not available on the amount of coal produced via surface mining; however, the amount appears to have been negligible. Surface mining reached 1% of bituminous (including sub-bituminous and lignite) production in 1917, and it first exceeded 10% of production in 1941. For year-by-year figures, see:
 * Surface mining before 1950
 * Surface mining after 1950

Inadequacy of OSM mining and reclamation data
In 2007, two environmental groups with long experience in mining issues, the Western Organization of Resource Councils and the Natural Resources Defense Council, published a report reviewing the first 30 years of the Surface Mining Control and Reclamation Act. The report criticized the quality of the data on mining available from the Office of Surface Mining:


 * First, OSM regularly failed to include critically important data in its published reports. For example, the number of acres disturbed by mining is a critical piece of information for anyone interested in reviewing SMCRA’s implementation and OSM’s performance, particularly with regard to reclamation. Prior to 1998, OSM did not publish the number of mined acres in its annual national reports, although it did publish the number of acres reclaimed. From 1998 through 2002, data about how many acres had been affected by mining (“disturbed acres”) as well as the number of acres reclaimed were included in annual reports, allowing readers to easily evaluate for themselves how well SMCRA’s reclamation goals were being achieved. In 2003, however, the agency stopped including information about acreage mined in its national reports despite its significance. Similarly, inspection information for active and inactive coal mines is critical because OSM’s regulations impose different inspection requirements for these types of mines. Yet OSM failed to separate inspection data according to active and inactive mine status on a consistent basis. Its national reports do not include this information but rather present cumulative data. Moreover, 40 percent of the state annual oversight reports the agency published over the past 10 years did not contain these data. Second, the data that were published were often problematic. In particular, there were numerous inconsistencies between OSM’s annual reports and the state oversight reports upon which they are supposed to be based. According to the agency, “state oversight reports are the sole source of data for the regulatory information and data tables in the Annual Report for those states with regulatory primacy.” Yet when we compared the acreage data published in OSM’s national reports with the corresponding data in its annual oversight reports for all five states for the years 1996 to 2005, we found that 35.3 percent of the figures in the national reports did not match the corresponding data in the state reports. Indeed, for the years 1998 to 2002, the “disturbed acreage” figures published in the national reports never once matched the corresponding numbers in the state oversight reports. Upon questioning, OSM explained that, because the reporting cycle for the annual report is different from that of the oversight reports, field offices are sometimes forced to give premature or estimated data to the national office for publication in the former. However, no explanation was provided for the different reporting cycles or for the agency’s failure to amend the annual reports when accurate data were available. These and other data problems suggest that OSM does not take seriously its responsibility to provide information that “stand[s] up to independent, objective external inspection.”

Related SourceWatch articles

 * Coal mine reclamation
 * Concentrating solar power land use
 * Mountaintop removal
 * Surface mining before 1950
 * Surface mining after 1950
 * Surface Mining Control and Reclamation Act

External resources

 * Harris Epstein, Johanna Wald, John Smillie, "Undermined Promise: Reclamation and Enforcement of the Surface Mining Control and Reclamation Act 1977-2007," Natural Resources Defense Council and Western Organization of Resource Councils, 2007
 * Extent of Mountaintop Mining in Appalachia - 2009, Appalachian Voices
 * Office of Surface Mining Reclamation and Enforcement Annual Reports
 * James F. Fox and J. Elliott Campbell, "Terrestrial Carbon Disturbance from Mountaintop Mining Increases Lifecycle Emissions for Clean Coal," Environ. Sci. Technol., 2010, 44 (6), pp 2144–2149, February 8, 2010